In many cases it is desirable for containers to be easily recloseable. The most desirable type of reclosure, so far as the user is concerned, is one which can be placed over the access aperture of the container and turned to effect reclosure, for example a screw cap of which many kinds are available. However, it has been necessary, in order to satisfactorily apply a screw-type reclosure to a metal container body, to form some kind of screw thread around the upper part of the container body wall. In production, this is a relatively slow process and adds significantly to the cost of the container. Also, if it is desired to have a printed or other decorative finish extending right to the top of the container, the screw threading operation has to be carried out in an area where the finish has already been applied and consequently the finish is readily damaged.
Further, many products including food stuffs require to be packed in metal containers which are hermetically sealed yet easy to open. This has been done in recent years using the well-known ring-pull closure, a ring of which is pulled in order to tear away a part of the hermetically sealed lid of the container. This type of closure is destroyed on opening and therefore requires an additional re-closure after the lid has been broken open.